Grey Line Propagation

I am currently working on grey line propagation studies as part of my work with the RSGB's Propagation Studies Committee. For those who do not know what grey line is, here is a feature that has been written for the RSGB's RadCom magazine. It is available in HTML form without images here or as an Adobe Acrobat PDF file with images (701kb) here.

Feel free to download them.

The first part of the research is looking at trans-terminator propagation on 10m. That is, signal enhancements that are sometimes seen when signals arrive from areas to the west that are currently experiencing their local sunset. For this, Geoclock software is used (see, but the parameters are changed to show the illumination at both the D and F layers. This is done by following the instructions in the package. Signals are logged using DL4YHF's excellent Spectrum lab software (see

The resultant data are processed using MS Excel and graphs can be produced like the one here. At the moment, enhancements have been seen on signals from the OH9TEN and SV3AQR beacons, but it doesn't happen every day. More research is needed. If you would like to take part in the research please email me at [email protected]. Research on grey line phenomena on the lower bands will take place in Autumn 2002


  • You can also look at the latest trans-terminator results on 3210kHz (October 2005).
  • Radcom published the results of the first round of tests in May 2005 - you can download it in PDF format (500kb)
  • Download the "3Y0X Propagation Predictions to G v Reality" presentation given at the RSGB's HF convention in October 2006 in either Adobe Acrobat PDF or Powerpoint formats (both 5mb). While not strictly about greyline it does show the effect of morning/sunrise enhancements on 80m very well.(October 2006)